The oldest woman in the top-100 is Queen Elizabeth II, who at age 92 ranked 23rd, while 28-year-old US pop star Taylor Swift was youngest at 68th.

US politician Hilary Clinton dropped out of the list for the first time since it started in 2004.

The top-100 women control or influence nearly 2 trillion US dollars in revenue and oversee some five million employees, Forbes said.

Forbes Executive Vice President Moira Forbes said the 2018 list reflects the volatile state of global business and politics.

"The world's most powerful women are leading amidst a tumultuous time where geopolitical tensions are on the rise, key economies are facing instability, and where trust in institutions is at an all-time low," she said.